AQUATIC PLANTS USEFUL TO THE MICROSCOPIST. 47 



in recognizing them, nor in learning their names, al- 

 though he may never have studied botany; he has only 

 to compare the leaves with the figures in this chapter. 

 It is, of course, understood that there are many 

 aquatic plants not here referred to, only those being 

 included in this list which afford the most certain sup- 

 ply of microscopic life. The leaves of many water- 

 plants fall against the stem and cling together when 

 lifted into the air; but if the student will place a small 

 part of the plant in a saucer ("individual butter" 

 dishes are good for this purpose), he can float them 

 out against the white surface and so compare them 

 with the figures. 



RANUNCULUS AQUATILIS (Fig. 6). 

 A part of the stem and a single leaf of this plant are 

 shown about natural size in the figure (Fig. 6). It is 

 not uncommon in ponds and slowly flowing streams. 

 The leaves are dissected 

 into fine, rather stiff and 

 hair-like parts, to which 

 many minute animals, 

 such as Rotifers (Chapter 

 VIII.), Vorticellas (Chap- 

 ter v.), and Stentors 

 (Chapter V.) are fond of 

 attaching themselves. 

 The leaves are placed 

 above each other on 

 opposite sides of the 

 long and rather brittle 

 stem, and usually rather 

 wide apart. The whole plant is under water ex- 

 cept at flowering time, when it raises a delicate stalk 



Fig. 6. — Leaf of Randnculus aqudtilis. 



